The invention is directed toward a cephalostat for positioning the patient between an x-ray tube and a film cassette so that cephalometric roentgenography may be accurately made and wherein sequential series of identical cephalometric views may be taken over time.
Cephalometric roentgenography of the type undertaken by dentists, and primarily those practicing orthodontistry, requires the utmost in precision and clarity as well as the rapid positioning of the patient with minimum inconvenience.
In order to accurately dispose the mid-sagital plane relative to the x-ray tube at a standard distance from the film, ear positioning posts are utilized in most cephalostat devices and include means for moving them relative to the patient in order that the skull is placed directly with the mid-sagital at a selected location. Additionally, a positioning of the Frankfort plane with respect to the horizontal is usually required to be made so that consistent, repetitive, sequential roentgenographic series may be taken. In conjunction with the positioning of the Frankfort plane and mid-sagital line, a nasion positioner is often provided. Also, to meet particular focusing, clarity and imaging requirements, the distance that the x-ray film cassette is disposed relative to the patient's head is preferably adjustable.
Usually, wall mounted x-ray tubes, supported by mechanical arms, are used in association with a fixator/collimator for accurate alignment limiting diffusion and minimizing the exposure area by the x-ray beam.
Cephalometric roentgenography is used by the general dentist although less frequently than by the more specialized orthodontist. A cephalostat that would serve the needs of both, and yet provide for precise positioning, clarity and minimum patient inconvenience, would be desirable.
In conjunction with serving the needs of both general and specialized use, it would also be desirable for the cephalostat to not only provide for taking the most common lateral cephalometric sequence, but also include the ability to position the patient for anterior and posterior exposures with the added benefit of being capable of positioning the patient for oblique pictures. In this regard, an adjustable mechanism for a cephalostat to selectively dispose the skull in said anterior, posterior, lateral and oblique arrangements, while consistently positioning the midsagital plane and Frankfort plane relative to the x-ray tube and film cassette, is highly preferred. An additional need in such a cephalostat device would be to provide for the demountability of the cephalostat from a wall mounting wherein efficient use of space in a dental office may be obtained when roentgenography is not required.
The ease with which a cephalostat is employed should include quick positioning of the patient with minimal inconvenience and apprehension. As a result, the movement of the earposts away from, and into contact with, the patient's ear canals, would be desirably accomplished with an easily accessible and very accurately-functioning adjustment means for moving the two earposts relative to each other.
In conjunction with the foregoing needs, it would be highly beneficial to provide for the variable movement of the nasion positioner inwardly and outwardly of the device to bring it closer to and away from the patient, as well as being able to vertically move a nose positioning flange into position at the bridge of the nose and then releasably lock in that position. Additionally, the housing means for such a cephalostat would also require that it include engagement means for attachment to supporting means on a wall. Also, it would be necessary that the housing means for the cephalostat accommodate an earpost adjustment mechanism, nasion adjustment mechanism, and further the ability to supportably accommodate cassette-holding tubes, or rods, for the positioning of an x-ray cassette holder at a selected distance from the mid-sagital plane.
Also, it would be desirable to provide an easily-used and simplified adjustable bracket means for the x-ray film cassette holder whereby to vertically move an x-ray film cassette relative to the patient's skull for accommodation of both children and adults, as well as the ability to hold an x-ray cassette, which is usually rectangular, either lengthwise or sideways.
Moreover, the movements and adjustments of the x-ray cassette holder, nasion positioning means, earposts means, and wall mounting engageable means, would necessarily involve a desirable combination with a rotational adjustment capability for the housing means whereby to position the patient's head in a range of angular positions relative to the x-ray tube whereby the earposts mechanism and nasion positioner move with one portion of the housing means, independently, and relatively to a separately supported film cassette holder in order to rotate the properly positioned skull at varying angles relative to the x-ray film held by the cassette holder.
All the foregoing adjustments must be made precisely, and quickly but yet be combined in a device which is compatible with a wide range of dental office arrangements and usable with existing wall mounted x-ray tube arm assemblies. These goals would also be preferably achieved by a device that is economically attractive and useful to almost all dental practitioners.
In accomplishing the foregoing objectives, it would also be desirable to provide a very compact cephalostat, having all the noted adjustment features, and in which simplified, but precise, adjustments can be made without the need for expensive and elaborate gearing and other adjustable mechanisms that could require extra repair and maintenance expenses in order to keep the devices in adjustment over time.
The present invention satisfies all the foregoing goals and objectives and provides a very compact, precise wall demountable cephalostat, having quick adjustment of an earpost mechanism, and the ability to angularly adjust a housing means whereby the patient's head may be placed at anterior, posterior, lateral, as well as oblique positions, relative to a separately adjustable and movable x-ray cassette holder. The invention also provides a double housing construction that permits one portion of the housing to be movable relative to the other whereby a nasion positioner and the earpost mechanisms may be moved to position the patient's head relative to a vertically and horizontally adjustable x-ray cassette holder that is mounted to a fixed housing portion of the cephalostat. The fixed portion of the housing means includes engageable means for attachment of support rods to be demountably engaged to a wall support plate means. Furthermore, the adjustment of the earpost mechanisms relative to the ear canals is manually achieved with an adjustment knob means located at the top of the fixed housing and arranged adjacent an adjustment means for the angular positioning of the second housing portion relative to the first, so that both adjustment means are thereby in close proximity for quick and precise use by the practitioner. In addition, an adjustment mechansim for a nasion positioner is provided with adjustment means conveniently located a short distance in front of the double housing means and wherein the fixed housing means also includes adjustable support means for sliding the cassette holder relative to the patient's head. The adjustable support means for the cassette holder is also in close convenient location to the nasion positioning adjustment, to the earpost adjustment means, and to the adjustable rotational positioning means for the double housing portions.
The invention may be summarized in part as comprising a wall-mounted cephalostat having a fixed upper, or first, housing portion mounted to rod means detachably supported at a wall plate means and a relatively movable second or lower housing portion rotatable relative to the first portion by a top-mounted adjustment knob means arranged on a shaft extending from the second housing portion to project upwardly and outwardly of the first housing. Further, a gear and rack means communicates with the lower end of the shaft interiorly of the second housing means. The gear and rack means are joined to two opposing earpost means and are able to move one relative to the other to firstly allow space under the housing means for the placement of the patient's head followed by the closure of the earpost means by oppositely rotating the adjustment knob means. The earpost means position the patient's head centrally below the bottom housing and at a consistent distance from the focal point of the x-ray tube that is wall mounted at a standard distance away from the cephalostat. The rotational adjustment of the second housing relative to the first housing is provided by an apertured index plate means rotably positioned atop the first housing and mounted with an upstanding hub of the second portion that extends through the first housing portion for supporting the second housing portion therethrough. Indexing holes are provided through a top wall of the first housing and a lock pin means is selectively insertable through the index plate means so that when the index aperture of the index plate means matches a hole on the top of the first housing, the pin means may be inserted to releasably lock the housings relative to each other in a desired relative angular positioning. A nasion positioner means is laterally positionable relative to the bottom housing means by the provision of slide rod means extending inwardly of the bottom, or second, housing but spaced to be out of the way of the gear and rack adjustment mechanism, and wherein a vertical nose slide for a nose bridge positioning portion includes a locking means for both the nose slide and slide rods whereby the nasion positioner may be jointly locked both laterally and vertically relative to the cephalostat housing portions. The first, or upper, housing body also includes cavity means, movably-accommodating slide rod means extending therethrough and supporting laterally thereof an adjustable, x-ray cassette holding means, in which an x-ray film cassette may be moved laterally and vertically relative to the housing body means. An engagement means is provided by the upper housing for engaging the ends of support rods that are connected at opposite ends to a wall mounting plate means, whereby the first housing supports the second housing, cassette holder means, earpost mechanism, and nasion positioner.
The first and second housing portions are compact but yet cooperate to provide several desirable adjustments, including: positioning of the gear rack by a top adjustment knob means for changing the earpost means position; slide rod means for moving the nasion positioner; slide rod means for moving the adjustable x-ray cassette holder; and, a pin and index plate means attached to the bottom housing hub and extending upwardly from the second through the first housing portion for the rotational adjustment of the second housing portion; whereby all may be adjusted in any sequence, or simultaneously, and without one impeding the adjustment of another. The relative positioning of the bottom housing to the top housing for anterior, posterior, lateral and frontal oblique roentgenography is further achieved by the placement therebetween of a lubricating pad means for aiding rotation relative therebetween. Similarly, the apertured index plate means, associated with an index pin means for indexing with holes in the top of the first body portion means, is rotatably carried by the second body portion hub means over the first body portion and includes lubrication therebetween for smooth rotation. The slide rod means facilitating the lateral motion of the x-ray cassette holder means, and the gear rack means facilitating the adjustment of the earposts, each include stop means whereby inadvertent disengagement from the housings is prevented. A unique simplified adjustment for the vertical positioning of an x-ray film cassette, and for accommodating the cassette lengthwise or sideways, is provided at the x-ray cassette holder means by virtue of two slots slidably engaged by opposing, preferably U-shaped, holders which are releasably secured by lock knob means, whereby the holders are vertically movable relative to each other by adjusting the lock knob means. An adjustment means of the nasion positioner makes possible the locking of the horizontal slide rod means by biasing the rod means against a friction fit bushing sleeve supportably extending inwardly of the second housing. The adjustment means serves the dual purpose of also locking a vertical nose slide member relative to the bridge of the patient's nose wherein both horizontal and vertical locking of the nasion positioner is achieved by one adjustment means. Additionally, the first and second housing body portions may be complementarily shaped to provide smooth, flush, outer exterior wall conformations with rounded corners, and wherein the bottom, or second housing, portion may be rotated relative to the first with allowance for rotational clearance of the nasion positioner around the first housing in order to expedite taking frontal oblique, anterior, posterior and lateral x-ray pictures in quick succession.